Plastic Expansion Nuts are rugged nylon fasteners for applications where metal to metal contact is not desired. Insertion versus retention ratio is not as high as metal expansion nuts; however, screw threads are protected from corrosion or galvanic action because they are completely enclosed in plastic. This also eliminates the danger of wire chafing or scratching on sharp screw cutting edges. Ideal for front-mounted attachments, they are self-retaining and easy to apply. These expansion nuts use No. 8 or No.10 sheet metal screws, and resist pull up to 200 pounds.